1. Field of the Invention
The present invention relates to a unit for a programmed-controlled feed-through machine. More particularly, the present invention relates to an edge-routing unit for a program-controlled feed-through machine.
2. Description of the Prior Art
DE 40 30 138 A1 teaches a machine having an edge-routing unit of a generic type. Such a routing unit is controlled via a feeling device having a feeler wheel, as can be seen more clearly from U.S. Pat. No. 2,839,107.
For exact flush routing of an edge strip glued onto narrow surface sides of workpieces, it is not sufficient, on one hand, to preset paths to be covered in an X-axis and a Z-axis with a routing tool in a machine control program and, on the other hand, to merely follow up with the routing tool along a workpiece contour sensed by a feeler wheel.
In this case, it has to be taken into account that, in a direction of the X-axis of the machine, a relevant positioning device mainly controls running of the routing tool together with a respective workpiece to be machined over a short distance. In addition, a path contour to be covered is preset by the program control of the machine so as to be smaller than a workpiece outline, so that there is a feeling clearance due to an undersize relative to a theoretical workpiece outline. This feeling clearance being necessary so that a more accurate follow-up of the routing tool according to an actual workpiece outline contour is possible via the feeler wheel.
An entire path positioning of the routing tool has its own dynamics, which, during changes in direction at the workpiece contour, in particular at corners or rounded portions having a small radius of curvature, leads to inaccuracies at workpiece corners lying at a front and a rear in a workpiece feed-through direction. Thus, too much of the edge strip may be removed at one location, in which case the routing tool starts to cut panel material. At another location, a projection of the edge strip relative to an adjoining workpiece surface may remain.
In order to be able to partly compensate for such errors during flush routing, the routing tool is adjustable relative to the feeler wheel in known edge-routing units. Consequently, at least as viewed in a direction transversely to the X-axis of the machine, that is to say, in the direction of the Y-axis, the routing tool is not located where the feeler wheel travels over a workpiece surface, and therefore cutting operation with the routing tool does not take place exactly where sensing of the workpiece is effected.
Depending on whether the edge-routing unit, in addition to one of two longitudinal edges of the edge strip, is provided for trimming either that edge of the edge strip which lies at the front in the feed-through direction or that edge of the edge strip which lies at the rear in the feed-through direction, lengths of which edges depend on thickness of the workpiece, either a certain advance of the feeler wheel or a lag of the feeler wheel relative to the routing tool is firmly set. This requires empirical determination during trial passes of workpieces and a manual adjustment of the routing tool relative to the feeler wheel when the machine is stopped, which is associated with considerable set-up times when changing over the edge-routing unit to a respective workpiece configuration.
Nonetheless, such firmly set corrections of routing inaccuracies, when machining operation is taking place, lead to a situation in which compensation of a routing inaccuracy at one location entails a routing error at another location, for which reason considerable effort is required to work out an optimum of requisite corrections.